Evenin ,looking for some help identifying this Sylvania amp and pre console pull.Friend of mine had this amp and pre for a while and had told me i could have them .He couldnt find them .Lo and behold he did.He has done some custom work to it speaker binding posts and new rca jacks and side and front and rear panels .No other work has been .Tube compliment is 4 6BQ5 marked sylvania Made in Enland 2 6BL8 maeked sylvania mi England and a single 7025,marked sylvania USA and a 5U4GB rctifier sylvania usa.The amp has set of rca input and output trying to put up pix any help would be apreciated.Im kinda of new with tubes.Also if anybody knows an AKer here in South FL that does work on equip...tube or SS...having a very hard time finding someone with exp and reliability
unknown Sylvania amp and pre console pull
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Shadowdog
Super Member
You can learn how to repair & troubleshoot by diy if your careful with unplugging it when working on it. Just make sure PS (power supply) caps are discharged with say a 100K to 200K resistor soldered to a piece of wire.
A good soldering station is well worth buying for under $100 like a 51 series Weller and Haako 888 which both have adjustable temp. They make soldering easy! A good solder sucker is good to have also.
Check out the tubelab.com site for good soldering instructions also.
Here is a general rebuilding guide:
Jim of Jim McShane Tubes will make a kit of parts up for you to rebuild it if you contact him. He is a great guy to deal with and is well known for his HK Citation kits & well tested tubes.
(1) Old tube amps shouldn't just be plugged in as old capacitors can take out Transformers (s) and Tubes.
(2) Always have a load on the speaker outputs (25W + 16 ohm resistors if testing) as you can take out Output Transformers
(3) Always Wait 5 minutes (or more till tubes are cold) after shutting amp off before powering up again as the Tubes and if not lucky Transformers can suffer fatal damage. Caps can also be damaged. Basically the tubes are still conducting (regulate voltage) when warm and if started up again they can conduct at the wrong time or way.
Anyway if you want to power it up safely also clean all tube sockets and pins for best results.
You need a dim bulb tester in line with a variac to do it safely. The bulb is to help warn of a short condition.
You can get away with just light bulbs, but the variac is great to have!
Before recapping (Power Supply including can caps, bias caps , & coupling caps) and checking resistors take Lots of Detailed Pictures.
You can do it, by replacing one or two caps at a time, then checking for correct operation.
Can caps can be unhooked and left for looks with new caps strapped under chassis (this is a lot cheaper also) Jim may set you up with modern big caps clamped in place of the old ones. Some people like to re stuff the can caps with small skinny ones , but guys like Jim say the modern big caps(big round caps in the same diameter as the old can ones) like the JJ's, Panasonic etc work better sonically.
Heyseed hamfest is supposed to make really nice reproductions of the old can caps.
Resistors usually go high in value so they can be checked in circuit.
Pot's and switches should be cleaned with the right cleaners also as they can cause many problems.
Any selenium rectifiers that are usually used in fixed bias supplies usually should also be replaced with modern SS diodes.
Just start studying the schematics so you can learn to trace the circuit wiring.
A good soldering station is well worth buying for under $100 like a 51 series Weller and Haako 888 which both have adjustable temp. They make soldering easy! A good solder sucker is good to have also.
Check out the tubelab.com site for good soldering instructions also.
Here is a general rebuilding guide:
Jim of Jim McShane Tubes will make a kit of parts up for you to rebuild it if you contact him. He is a great guy to deal with and is well known for his HK Citation kits & well tested tubes.
(1) Old tube amps shouldn't just be plugged in as old capacitors can take out Transformers (s) and Tubes.
(2) Always have a load on the speaker outputs (25W + 16 ohm resistors if testing) as you can take out Output Transformers
(3) Always Wait 5 minutes (or more till tubes are cold) after shutting amp off before powering up again as the Tubes and if not lucky Transformers can suffer fatal damage. Caps can also be damaged. Basically the tubes are still conducting (regulate voltage) when warm and if started up again they can conduct at the wrong time or way.
Anyway if you want to power it up safely also clean all tube sockets and pins for best results.
You need a dim bulb tester in line with a variac to do it safely. The bulb is to help warn of a short condition.
You can get away with just light bulbs, but the variac is great to have!
Before recapping (Power Supply including can caps, bias caps , & coupling caps) and checking resistors take Lots of Detailed Pictures.
You can do it, by replacing one or two caps at a time, then checking for correct operation.
Can caps can be unhooked and left for looks with new caps strapped under chassis (this is a lot cheaper also) Jim may set you up with modern big caps clamped in place of the old ones. Some people like to re stuff the can caps with small skinny ones , but guys like Jim say the modern big caps(big round caps in the same diameter as the old can ones) like the JJ's, Panasonic etc work better sonically.
Heyseed hamfest is supposed to make really nice reproductions of the old can caps.
Resistors usually go high in value so they can be checked in circuit.
Pot's and switches should be cleaned with the right cleaners also as they can cause many problems.
Any selenium rectifiers that are usually used in fixed bias supplies usually should also be replaced with modern SS diodes.
Just start studying the schematics so you can learn to trace the circuit wiring.
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WOO-Hooo
thanx much Markus the sams would be much apreciated let me know if i need to do something...im still a little confused bout the input ,output on the amp and the input outputs on the pre .The preamp tuner only has the phono and tuner on the input selector.The amp has been brought up and sounds ok... there is some almost fm static noise pretty stedy coming out of the amp...this thing seems to have a bit of juice for its size,I have tried it with the pretuner and a different preamp.Would love to get this sucker working corectly.. thanx for the reply ...hope ya find it
Before the great console purge I had this amp and the phone-only console..... I have the sams folder somewhere...... Its basically a push pull el84 amp and the 7025 is an extra gain stage for the preamp. Lemme see what I can find
thanx much Markus the sams would be much apreciated let me know if i need to do something...im still a little confused bout the input ,output on the amp and the input outputs on the pre .The preamp tuner only has the phono and tuner on the input selector.The amp has been brought up and sounds ok... there is some almost fm static noise pretty stedy coming out of the amp...this thing seems to have a bit of juice for its size,I have tried it with the pretuner and a different preamp.Would love to get this sucker working corectly.. thanx for the reply ...hope ya find it
markus
Master Procrastinator
Just for grins try bypassing the 7025 preamp tube... Plug a cd player or ipod directly before the 6bl8 tubes... you should see the outgoing signal wire from the preamp plugs into RCA jack's directly before the 6bl8...
IIRC this got rid of alot of the bbackground noise for me....
IIRC this got rid of alot of the bbackground noise for me....